Positional strategy of trunk muscles among aquatic,semi-aquatic and terrestrial species in Urodela

Clarification of the trunk structure in Urodela is important in understanding the locomotive evolution of basal tetrapods. The components of the muscular trunk wall among Urodela using different modes of locomotion were compared. Since the whole trunk may be used for swimming and the effect of limbs may be small in the more aquatic species, they showed smaller differences in the trunk muscles among anterior, middle and posterior sections of the trunk. By contrast, in the more terrestrial species, the dorsal and abdominal muscles are larger in the middle section than those in the anterior and posterior sections. High compressive stresses occur in the supporting limbs and their insertion at the trunk on the ventral side, and spread from the forelimbs along the back to the supporting hindlimbs on the dorsal side. Tensile stresses occur in the middle ventral part. The components of the trunk muscles among the three sections may reflect differences in stresses occurring in the trunk of the more terrestrial species. The findings also suggest that in the middle section, larger dorsal muscles for stiffening the back to maintain posture and larger abdominal muscles are responsible for balancing the body weight while it is supported by the limbs in the more terrestrial species.     

Amphibian conservation: Are we on the right track?

Amphibian declines and extinctions are a worldwide concern. Conservation priorities for amphibians should target threatened taxa (taxonomic targets) and regions with high levels of species endemism (geographical targets). Does published research on amphibian conservation reflect the global taxonomic and geographic priorities? I surveyed six years (2000-2005) of 10 conservation and herpetological journals (Amphibia-Reptilia, Animal Conservation, Applied Herpetology, Biodiversity and Conservation, Biological Conservation, Conservation Biology, Copeia, Herpetologica, Journal of Herpetology and Oryx), and analyzed all articles on amphibians. Attention indexes were calculated for orders, threatened species and biogeographic realms. I also examined how well research from tropical developing nations (with high levels of richness and endemism) are represented in the international literature. Attention indexes results show that the most studied amphibian order is Caudata, whereas Gymnophiona is the least studied one. The same trend is observed for threatened species, with threatened Caudata species receiving proportionally more attention than threatened Anura and Gymnophiona. The biogeographic realms that receive most attention by amphibian conservationists are: Oceania, Nearctic and Palearctic. However, the Neotropical, Afrotropical and Indomalayan are the regions with higher species diversity. Forty-one countries contributed articles, but the majority of amphibian conservation research is conducted by North American and western European researchers. There is urgent need for capacity building in tropical developing nations. Amphibians are more threatened and are declining more rapidly than either birds or mammals. However, amphibian conservation is still misplacing its focus in lower-biodiversity regions and non-threatened species. If such trends are not changed, the consequences for the persistence of amphibians worldwide may be dire.     

Length–mass allometries in amphibians

Body mass is rarely recorded in amphibians, and other body measurements (e.g. snout to vent length, SVL) are generally collected instead. However, length measurements, when used as proxies of body mass in comparative analyses, are problematic if different taxa and morphotypes are included. We developed allometric relationships to derive body mass from SVL measurements. We fitted phylogenetic generalized least square models for frogs (Anura) and salamanders (Caudata) and for several families separately. We tested whether allometric relationships differed between species with different habitat preferences and between morphs in salamanders. Models were fitted with SVL–mass measurements for 88 frog and 42 salamander species. We assessed the predictive performance of the models by cross‐validation. Overall, the models showed high explained variance and low forecasting errors. Models differed among semi‐aquatic, terrestrial and arboreal frogs, and between paedomorphic and non‐paedomorphic salamanders. Body mass estimates derived from our models allow for comparability of studies on multiple taxa and can be used for testing theories built upon evolutionary and ecological processes which are directly related to body mass.     

Spatial correlates of amphibian use of constructed wetlands in an urban landscape

Many amphibian species rely on both aquatic and terrestrial habitats to complete their life cycles. Therefore, processes operating both within the aquatic breeding habitat, and in the surrounding uplands may influence species distributions and community composition. Moreover, changes in land use adjacent to breeding site may degrade aquatic habitats. To assess land use effects on pond-breeding amphibian assemblages, we investigated relationships between land use, breeding habitat conditions, and breeding amphibian use of constructed wetlands in urban environments of the Baltimore metropolitan area, USA. Forest and impervious surface associations with species richness and occurrence occurred at spatial scales ranging from 50 to 1,000 m, with strongest relationships at 500 m. Forest and impervious surface cover within 1,000 m of ponds were also related to water and sediment quality, which in turn were capable of explaining a proportion of the observed variation in species richness and occurrence. Taken together, our results suggest that forest and other land covers within relatively proximal distances to ponds (i.e., within 50–1,000 m) may be influencing species richness directly via the provisioning of upland habitat, and indirectly via influences on within pond habitat quality. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.